In video that Israel's Channel 10 aired, the tunnel appeared to be wired for electricity and was high enough for a man to stand, walk or run though. An Israeli reporter who was inside the tunnel reported seeing markings and dates indicating the tunnel had been completed in July.

The Israeli military said the most likely use for such a tunnel would be to kidnap soldiers or civilians and take them back into Gaza to trade for Palestinian prisoners.

A similar tunnel was used to kidnap soldier Gilad Shalit in June 2006. His capture ended five years later after Israel released more than a thousand Palestinian prisoners.

The new tunnel increases concerns on the Israeli side for its sheer size and sophistication.

It is the third such tunnel found along the Gaza-Israel security fence in the past year, according to the military.

"The IDF operates under the notion that there are additional tunnels jeopardizing civilians and security personnel in the area," Brig. Gen. Mickey Edelstein, commander of the Gaza division, said in a statement.